Photoresists are light sensitive materials which are applied to a wide variety of substrates. They provide a chemically resistant pattern after exposure through a mask to light of suitable wave length and development. For example, they are used in the fabrication of semiconductor devices by applying a thin layer of photoresist to a wafer, contacting the desired mask with the layer, exposing and developing to provide a predetermined pattern on the wafer. However, there are disadvantages accompanying the use of photoresists in semiconductor manufacturing. For example, mask deterioration occurs due to adhesion of photoresisted wafers to the mask upon contact with the photoresist layer. This in turn substantially reduces the life of the mask. Furthermore, pieces of photoresist from previous wafers adhering to the mask frequently cause latent pinholes in negative photoresist to be printed in the photoresist pattern when the mask is reused. These pinholes not only decrease the yield of devices made from the wafers, but detract from the quality of the resulting devices. Thus, the pinholes left in the photoresist are etched in later processing to form potential electrical defects in semiconductor devices. For example, interlayer shorts in multilayer devices and "popcorn" noise due to unwanted junction formation in semiconductor doping and diffusion operations have been traced to pinholes in the photoresist.
Some of the aforementioned problems have been recognized and attempts made to overcome them by prior art researchers. For example, U.S. Pat. No. 3,652,273 describes the use of a polyvinyl butyral polymer as a protective top coat for photoresist layers. U.S. Pat. No. 3,458,311 teaches a protective coating containing polyvinyl alcohol and a surfactant having wetting properties; the coating is used for making printing plates.